A 



A-'iS 



i 



^RS^ 



Standard 
Specifications and Tests 



for 



Portland Cement 



of the 
American Society for Testing Materials 

Affiliated with the 
International Association for Testing Materials 
Philadelphia, Pa. 



These specifications are the result of several years' 
work of a special committee representing a United States 
Government Departmental Committee, the Board of 
Direction of the American Society of Civil Engineers, 
and Committee C-1 on Cement of the American Society 
for Testing Materials, in cooperation with Committee C-1. 



"Concrete for Permanence" 

Reprinted by 

Portland Cement Association 

DECEMBER. 1916 



ATLANTA 

Hurt Building 
INDIANAPOLIS 

Merchants Bank Building 
PARKERSBURG, W. VA. 

Union Trust Building 



Offices at 

CHICAGO 

111 W. Wasliington Street 
KANSAS CITY 

Commerce Building 
PITTSBURGH 

Farmers Bank Building 



DALLAS 

Soutliwestern Life Building 
NEW YORK 

101 Park Avenue 
SAN FRANCISCO 

116 New Montgomery Street 



Authorized Reprint from the Copyrighted 

A.S.T.M. Standards (1916) 

American Society for Testing Materials, 

Philadelphia, Pa. 

STANDARD SPECIFICATIONS AND TESTS FOR 
PORTLAND CEMENT.i 



Definition. 



Chemical 
Limits. 



. Serial Designation: C 9-17. 

1. Portland cement is the product obtained by finely pul- 
verizing clinker produced by calcining to incipient fusion an 
intimate and properly proportioned mixture of argillaceous and 
calcareous materials, with no additions subsequent to calcina- 
tion excepting water and calcined or uncalcined gypsum. 

I. CHEMICAL PROPERTIES. 

2. The following limits shall not be exceeded: 

Loss on ignition, per cent 4 . 00 

Insoluble residue, per cent . 85 

Sulfuric anhydride (SO3), per cent 2 . 00 

Magnesia (MgO), per cent 5 . 00 



Specific Gravity. 



Fineness. 



Soundness. 



Time of Setting. 



Tensile Strength. 



11. PHYSICAL PROPERTIES. 

3. The specific gravity of cement shall be not less than 
3.10 (3.07 for white Portland cement). Should the test of 
cement as received fall below this requirement a second test may 
be made upon an ignited sample. The specific gravity test will 
not be made unless specifically ordered. 

4. The residue on a standard No. 200 sieve shall not exceed 
22 per cent by weight. 

5. A pat of neat cement shall remain firm and hard, and 
show no signs of distortion, cracking, checking, or disintegration 
in the steam test for soundness. 

6.. The cement shall not develop initial set in less than 45 
minutes, when the Vicat needle is used or 60 minutes when the 
Gillmore needle is used. Final set shall be attained within 10 
hours. 

7. The average tensile strength in pounds per square inch 
of not less than three standard mortar briquettes (see Section 51) 

1 These specifications and tests were adopted by letter ballot of the Society on September 
1, 1916, with the understanding that they will not become effective till January 1, 1917. 

(2) 



i: 



Specifications and Tests for Portland Cement. 3 

composed of one part cement and three parts standard sand, by 
weight, shall be equal to or higher than the following: 



Age at Test, 
days. 



Storage of Briquettes. 



1 day in moist air, 6 days in water. . 
1 day in moist air, 27 days in water. 



Tensile Strength, 
lb. per sq. in. 



200 
300 



8. The average tensile strength of standard mortar at 28 
days shall be higher than the strength at 7 days. 

III. PACKAGES, MARKING AND STORAGE. 

9. The cement shall be deHvered in suitable bags or barrels Packages and 
with the brand and name of the manufacturer plainly marked *'^°s. 
thereon, unless shipped in bulk. A bag shall contain 94 lb. net. 

A barrel shall contain 376 lb. net. 

10. The cement shall be stored in such a manner as to per- storage, 
mit easy access for proper inspection and identification of each 
shipment, and in a suitable weather-tight building which will 
protect the cement from dampness. 

IV. INSPECTION. 

1 1 . Every f aciHty shall be provided the purchaser for care- inspection, 
ful sampling and inspection at either the mill or at the site of 

the work, as may be specified by the purchaser. At least 10 
days from the time of sampling shall be allowed for the com- 
pletion of the 7-day test, and at least 31 days shall be allowed 
for the completion of the 28-day test. The cement shall be 
tested in accordance with the methods hereinafter prescribed. 
The 28-day test shall be waived only when specifically so ordered. 

V. REJECTION. 

12. The cement may be rejected if it fails to meet any of Rejection, 
the requirements of these specifications. 

13. Cement shall not be rejected on account of failure to 
meet the fineness requirement if upon retest after drying at 
100° C. for one hour it meets this requirement. 

14. Cement failing to meet the test for soundness in steam 



/^ 



Specifications and Tests for Portland Cement. 



Number of 
Samples. 



Method of 
Sampling. 



Treatment of 
Sample. 



may be accepted if it passes a retest using a new sample at any 
time within 28 days thereafter. 

15. Packages varying more than 5 per cent from the speci- 
fied weight may be rejected; and if the average weight of pack- 
ages in any shipment, as shown by weighing 50 packages taken 
at random, is less than that specified, the entire shipment may 
be rejected. 

TESTS. 

VI. SAMPLING. 

16. Tests may be made on individual or composite samples 
as may be ordered. Each test sample should weigh at least 
8 1b. 

17. {a) Individual Sample. — If sampled in cars one test 
sample shall be taken from each 50 bbl. or fraction thereof. 
If sampled in bins one sample shall be taken from each 100 bbl. 

{h) Composite Sample. — If sampled in cars one sample 
shall be taken from one sack in each 40 sacks (or 1 bbl. in each 
10 bbl.) and combined to form one test sample. If sampled in 
bins or warehouses one test sample shall represent not more 
than 200 bbl. 

18. Cement may be sampled at the mill by any of the 
following methods that may be practicable, as ordered:' 

{a) From the Conveyor Delivering to the Bin.— At least 8 lb. 
of cement shall be taken from approximately each 100 bbl. 
passing over the conveyor. 

{h) From Filled Bin& by Means of Proper Sampling Tubes. — 
Tubes inserted vertically may be used for sampHng cement to 
a maximum depth of 10 ft. Tubes inserted horizontally may be 
used where the construction of the bin permits. Samples shall 
be taken from points well distributed over" the face of the bin. 

(c) From Filled Bins at Points of Discharge. — Sufficient 
cement shall be drawn from the discharge openings to obtain 
samples representative of the cement contained in the bin, as 
determined by the appearance at the discharge openings of 
indicators placed on the surface of the cement directly above 
these openings before drawing of the cement is started. 

19. Samples preferably shall be shipped and stored in air- 
tight containers. Samples shall be passed through a sieve 



Specifications and Tests for Portland Cement. 5 

having 20 meshes per linear inch in order to thoroughly mix the 
sample, break up lumps and remove foreign materials. 

VII. CHEMICAL ANALYSIS. 

Loss on Ignition. 

20. One gram of cement shall be heated in a weighed cov- Method, 
ered platinum crucible, of 20 to 25-cc. capacity, as follows, 
using either method (a) or (b) as ordered: 

(a) The crucible shall be placed in a hole in an asbestos 
board, clamped horizontally so that about three-fifths of the 
crucible projects below, and blasted at a full red heat for 15 
minutes with an inclined flame; the loss in weight shall be 
checked by a second blasting for 5 minutes. Care shall be 
taken to wipe off particles of asbestos that may adhere to the 
crucible when withdrawn from the hole in the board. Greater 
neatness and shortening of the time of heating are secured by 
making a hole to fit the crucible in a circular disk of sheet plat- 
inum and placing this disk over a somewhat larger hole in an 
asbestos board. 

(b) The crucible shall be placed in a muffle at any tempera- 
ture between 900 and 1000° C. for 15 minutes and the loss in 
weight shall be checked by a second heating for 5 minutes. 

21. A permissible variation of 0.25 will be allowed, and all Permissible 
results in excess of the specified Hmit but within this permissible Sanation, 
variation shall be reported as 4 per cent. 

Insoluble Residue. 

22. To a 1-g. sample of cement shall be added 10 cc. of Method, 
water and 5 cc. of concentrated hydrochloric acid; the hquid 

shall be warmed until effervescence ceases. The solution shall 
be diluted to 50 cc. and digested on a steam bath or hot plate 
until it is evident that decomposition of the cement is complete. 
The residue shall be filtered, washed with cold water, and the 
filter paper and contents digested in about 30 cc. of a 5-per-cent 
solution of sodium carbonate, the liquid being held at a temper- 
ature just short of boiling for 15 minutes. The remaining 
residue shall be filtered, washed with cold water, then with a 
few drops of hot hydrochloric acid, 1:9, and finally with hot 



6 Specifications and Tests for Portland Cement. 

water, and then ignited at a red heat and weighed as the insoluble 
residue. 
Permissible 23. A permissible variation of 0.15 will be allowed, and all 

anation. j-gg^j^g j^ excess of the specified limit but within this permissible 
variation shall be reported as 0.85 per cent. 

Sulfuric Anhydride. 
Method. 24. One gram of the cement shall be dissolved in 5 cc. of 

concentrated hydrochloric acid diluted with 5 cc. of water, with 
gentle warming; when solution is complete 40 cc. of water 
shall be added, the solution filtered, and the residue washed 
thoroughly with water. The solution shall be diluted to 250 cc, 
heated to boiHng and 10 cc. of a hot 10-per-cent solution of 
barium chloride shall be added slowly, drop by drop, from a 
pipette and the boiling continued until the precipitate is well 
formed. The solution shall be digested on the steam bath until 
the precipitate has settled. The precipitate shall be filtered, 
washed, and the paper and contents placed in a weighed plat- 
inum crucible and the paper slowly charred and consumed 
without flaming. The barium sulfate shall then be ignited and 
weighed. The weight obtained multiplied by 34.3 gives the 
percentage of sulfuric anhydride. The acid filtrate obtained in 
the determination of the insoluble residue may be used for the 
estimation of sulfuric anhydride instead of using a separate 
sample. 
Permissible 25. A permissible variation of 0.10 will be allowed, and all 

Vanation. j-gsults in excess of the specified limit but within this permissible 
variation shall be reported as 2.00 per cent. 

Magnesia. 
Method. 26. To 0.5 g. of the cement in an evaporating dish shall 

be added 10 cc. of water to prevent lumping and then 10 cc. of 
concentrated hydrochloric acid. The liquid shall be gently 
heated and agitated until attack is complete. The solution 
shall then be evaporated to complete dryness on a steam or 
water bath. To hasten dehydration the residue may be heated 
to 150 or even 200° C. for one-half to one hour. The residue 
shall be treated with 10 cc. of concentrated hydrochloric acid 
diluted with an equal amount of water. The dish shall be 



Specifications and Tests eor Portland Cement. 7 

covered and the solution digested for ten minutes on a steam 
bath or water bath. The diluted solution shall be filtered and 
the separated silica washed thoroughly with water.^ Five cubic 
centimeters of concentrated hydrochloric acid and sufficient 
bromine water to precipitate any manganese which may be 
present, shall be added to the filtrate (about 250 cc). This 
shall be made alkaline with ammonium hydroxide, boiled until 
there is but a faint odor of ammonia, and the precipitated iron 
and aluminum hydroxides, after settling, shall be washed with 
hot water, once by decantation and slightly on the filter. Set- 
ting aside the filtrate, the precipitate shall be transferred by a 
jet of hot water to the precipitating vessel and dissolved in 
10 cc. of hot hydrochloric acid. The paper shall be extracted 
with acid, the solution and washings being added to the main 
solution. The aluminum and iron shall then be reprecipitated 
at boihng heat by ammonium hydroxide and bromine water in 
a volume of about 100 cc, and the second precipitate shall be 
collected and washed on the filter used in the first instance if 
this is still intact. To the combined filtrates from the hydrox- 
ides of iron and aluminum, reduced in volume if need be, 1 cc. 
of ammonium hydroxide shall be added, the solution brought 
to boiling, 25 cc. of a saturated solution of boiling ammonium 
oxalate added, and the boiling continued until the precipitated 
calcium oxalate has assumed a well-defined granular form. 
The precipitate after one hour shall be filtered and washed, then 
with the filter shall be placed wet in a platinum crucible, and 
the paper burned off over a small flame of a Bunsen burner; 
after ignition it shall be redissolved in hydrochloric acid and the 
solution diluted to 100 cc. Ammonia shall be added in slight 
excess, and the liquid boiled. The lime shall then be reprecipi- 
tated by ammonium o:5^alate, allowed to stand until settled, 
filtered and washed. The combined filtrates from the calcium 
precipitates shall be acidified with hydrochloric acid, concen- 
trated on the steam bath to about 150 cc, and made slightly 
alkaline with ammonium hydroxide, boiled and filtered (to 
remove a little aluminum and iron and perhaps calcium) . When 
cool, 10 cc of saturated solution of sodium-ammonium-hydrogen 
phosphate shall be added with constant stirring. When the 

1 Since this procedure does not involve the determination of silica, a second evaporation 
is'unnecessary. 



8 Specifications and Tests for Portland Cement. 

crystallin ammonium-magnesium orthophosphate has formed, 
ammonia shall be added in moderate excess. The solution shall 
be set aside for several hours in a cool place, filtered and washed 
with water containing 2.5 per cent of NH3. The precipitate 
shall be dissolved in a small quantity of hot hydrochloric acid, 
the solution diluted to about 100 cc, 1 cc. of a saturated solu- 
tion of sodium-ammonium-hydrogen phosphate added, and 
ammonia drop by drop, with constant stirring, until the pre- 
cipitate is again formed as described and the ammonia is in 
moderate excess. The precipitate shall then be allowed to stand 
about two hours, filtered and washed as before. The paper 
and contents shall be placed in a weighed platinum crucible, 
the paper slowly charred, and the resulting carbon carefully 
burned off. The precipitate shall then be ignited to constant 
weight over a Meker burner, of a blast not strong enough to 
soften or melt the pyrophosphate. The weight of magnesium 
pyrophosphate obtained multipKed by 72.5 gives the percentage 
of magnesia. The precipitate so obtained always contains some 
calcium and usually small quantities of iron, aluminum, and 
manganese as phosphates. 
Permissible 27. A permissible variation of 0.4 will be allowed, and all 

results in excess of the specified Hmit but within this permissible 
variation shall be reported as 5.00 per cent. 



Variation. 



VIII. DETERMINATION OF SPECIFIC GRAVITY. 

Apparatus. 28. The determination of specific gravity shall be made 

with a standardized Le Chatelier apparatus which conforms to 
the requirements illustrated in Fig. 1 . This apparatus is stand- 
ardized by the United States Bureau of Standards. Kerosene 
free from water, or benzine not lighter than 62° Baume, shall 
be used in making this determination. 

Method. 29. The flask shall be filled with either of these liquids to 

a point on the stem between zero and one cubic centimeter, 
and 64 g. of cement, of the same temperature as the liquid, 
shall be slowly introduced, taking care that the cement does 
not adhere to the inside of the flask above the liquid and to 
free the cement from air by rolHng the flask in an inclined 
position. After all the cement is introduced, the level of the 
liquid will rise to some division of the graduated neck; the 



Specifications and Tests for Portland Cement. 




Have two 0.1 cc 
Graduations exiend 
above 1 and 

below Ma^k■■--^ 



Capacii■y 
of Bulk 
approx. 
250 cc 



|< 9 cm - - - ->) 

Fig. 1. — Le Chatelier Apparatus. 



10 Specifications and Tests for Portland Cement. 

difference between readings is the volume displaced by 64 g. 
of the cement. 

The specific gravity shall then be obtained from the formula 

r. .n ■ Weight of cement (g.) 

Specific gravity=— -— ^ — 

Displaced volume (cc.) 

30. The flask, during the operation, shall be kept immersed 
in water, in order to avoid variations in the temperature of 
the Hquid in the flask, which shall not exceed 0°.5 C. The 
results of repeated tests should agree within 0.01. 

31. The determination of specific gravity shall be made on 
the cement as received; if it falls below 3.10, a second deter- 
mination shall be made after igniting the sample as described 
in Section 20. 

IX. DETERMINATION OF FINENESS. 

Apparatus. 32. Wire cloth for standard sieves for cement shall be 

woven (not twilled) from brass, bronze, or other suitable wire, 
and mounted without distortion on frames not less than 1| in. 
below the top of the frame. The sieve frames shall be circular, 
approximately 8 in. in diameter, and may be provided with a 
pan and cover. 

33. A standard No. 200 sieve is one having nominally an 
0.0029-in. opening and 200 wires per inch standardized by the 
U. S. Bureau of Standards, and conforming to the following 
requirements : 

The No. 200 sieve should have 200 wires per inch, and the 
number of wires in any whole inch shall not be outside the 
limits of 192 to 208. No opening between adjacent parallel 
wires shall be more than 0.0050 in. in width. The diameter of 
the wire should be 0.0021 in. and the average diameter shall not 
be outside the Hmits 0.0019 to 0.0023 in. The value of the 
sieve as determined by sieving tests made in conformity with 
the standard specification for these tests on a standardized 
cement which gives a residue of 25 to 20 per cent on the 
No. 200 sieve, or on other similarly graded material, shall not 
show a variation of more than 1.5 per cent above or below the 
standards maintained at the Bureau of Standards. 

Method. 34. The test shall be made with 50 g. of cement. The 

sieve shall be thoroughly clean and dry. The cement shall be 



Specifications and Tests for Portland Cement. 11 

placed on the No. 200 sieve, with pan and cover attached, if 
desired, and shall be held in one hand in a slightly inclined posi- 
tion so that the sample will be well distributed over the sieve, 
at the same time gently striking the side about 150 times per 
minute against the palm of the other hand on the up stroke. 
The sieve shall be turned every 20 strokes about one-sixth of a 
revolution in the same direction. The operation shall continue 
until not more than 0.05 g. passes through in one minute of 
continuous sieving. The fineness shall be determined from the 
weight of the residue on the sieve expressed as a percentage of 
the weight of the original sample. 

35. Mechanical sieving devices may be used, but the cement 
shall not be rejected if it meets the fineness requirement when 
tested by the hand method described in Section 34. 

36. A permissible variation of 1 will be allowed, and all Permissible 
results in excess of the specified limit but within this permissible Sanation, 
variation shall be reported as 22 per cent. 

X. MIXING CEMENT PASTES AND MORTARS. 

37. The quantity of dry material to be mixed at one time Method, 
shall not exceed 1000 g. nor be less than 500 g. The propor- 
tions of cement or cement and sand shall be stated by weight in 
grams of the dry materials; the quantity of water shall be 
expressed in cubic centimeters (l cc. of water = 1 g.). The dry 
materials shall be weighed, placed upon a non-absorbent surface, 
thoroughly mixed dry if sand is used, and a crater formed in 

the center, into which the proper percentage of clean water shall 
be poured; the material on the outer edge shall be turned into 
the crater by the aid of a trowel. After an interval of J minute 
for the absorption of the water the operation shall be completed 
by continuous, vigorous mixing, squeezing and kneading with 
the hands for at least one minute.^ During the operation of 
mixing, the hands should be protected by rubber gloves. 

38. The temperature of the room and the mixing water 
shall be maintained as nearly as practicable at 21° C. (70° F.). 

1 In order to secure tiniformity in the results of tests for the time of setting and tensile 
strength the manner of mixing above described should be carefully followed. At least one 
minute is necessary to obtain the desired plasticity which is not appreciably affected by con- 
tinuing the mixing for several minutes. The exact time necessary is dependent upon the 
personal equation of the operator. The error in mixing should be on the side of over mixing. 



12 Specifications and Tests for Portland Cement. 

XI. NORMAL CONSISTENCY. 

Apparatus. 39. The Vicat apparatus consists of a frame A (Fig. 2) 

bearing a movable rod B, weighing 300 g., one end C being 
1 cm. in diameter for a distance of 6 cm., the other having a 
removable needle D, 1 mm. in diameter, 6 cm. long. The rod 




J^ 




Fig. 2. — Vicat Apparatus. 



is reversible, and can be held in any desired position by a screw 
E, and has midway between the ends a mark F which moves 
under a scale (graduated to milhmeters) attached to the frame A . 
The paste is held in a conical, hard-rubber ring G, 7 cm. in diam- 
eter at the base, 4 cm. high, resting on a glass plate H about 
10 cm. square. 



Specifications and Tests for Portland Cement. 13 



40. In making the determination, 500 g. of cement, with a Method, 
measured quantity of water, shall be kneaded into a paste, as 
described in Section 37, and quickly formed into a ball with 
the hands, completing the operation by tossing it six times from 
one hand to the other, maintained about 6 in. apart; the ball 
resting in the palm of one hand shall be pressed into the larger 
end of the rubber ring held in the other hand, completely filHng 
the ring with paste; the excess at the larger end shall then be 
removed by a single movement of the palm of the hand; the 
ring shall then be placed on its larger end on a glass plate and 
the excess paste at the smaller end sHced off at the top of the 
ring by a single obHque stroke of a trowel held at a sHght angle 

Table I. — Percentage of Water for Standard Mortars. 



Percentage of Water 
for Neat Cement 
Paste of Normal 
Consistency 


Percentage of Water 
for One Cement, 
Three Standard Ottawa 
Sand. 


Percentage of Water 
for Neat Cement 
Paste of Normal 
Consistency. 


Percentage of Water 

for One Cement, 

Three Standard Ottawa 

Sand. 


15 


9.0 


23 


10.3 


16 


9.2 


24 


10.5 


17 


9.3 


25 


10.7 


18 


9.5 


26 


10.8 


19 


9.7 


27 


11.0 


20 


9.8 


28 


11.2 


21 


10.0 


29 


11.3 


22 


10.2 


30 


11.5 



with the top of the ring. During these operations care shall be 
taken not to compress the paste. The paste confined in the 
ring, resting on the plate, shall be placed under the rod, the 
larger end of which shall be brought in contact with the surface 
of the paste; the scale shall be then read, and the rod quickly 
released. The paste shall be of normal consistency when the 
rod settles to a point 10 mm. below the original surface in 
i minute after being released. The apparatus shall be free 
from all vibrations during the test. Trial pastes shall be made 
with varying percentages of water until the normal consistency 
is obtained. The amount of water required shall be expressed 
in percentage by weight of the dry cement. 

41. The consistency of standard mortar shall depend on the 



14 Specifications and Tests for Portland Cement. 

amount of water required to produce a paste of normal con- 
sistency from the same sample of cement. Having determined 
the normal consistency of the sample, the consistency of stand- 
ard mortar made from the same sample shall be as indicated in 
Table I, the values being in percentage of the combined dry 
weights of the cement and standard sand. 

XII. DETERMINATION OF SOUNDNESS.^ 
Apparatus. 42. A steam apparatus, which can be maintained at a tem- 

perature between 98 and 100° C, or one similar to that shown 
in Fig. 3, is recommended. The capacity of this apparatus may 
be increased by using a rack for holding the pats in a vertical 
or incKned position. 
Method. 43. A pat from cement paste of normal consistency about 

3 in. in diameter, ^ in. thick at the center, and tapering to a 
thin edge, shall be made on clean glass plates about 4 in. square, 
and stored in moist air for 24 hours. In molding the pat, the 
cement paste shall first be flattened on the glass and the pat 
then formed by drawing the trowel from the outer edge toward 
the center. 

44. The pat shall then be placed in an atmosphere of steam 
at a temperature between 98 and 100° C. upon a suitable sup- 
port 1 in. above boiling water for 5 hours. 

45. Should the pat leave the plate, distortion may be 
detected best with a straight edge applied to the surface which 
was in contact with the plate. 

XIII. DETERMINATION OF TIME OF SETTING. 

46. The following are alternate methods, either of which 
may be used as ordered: 

Vicat 47. The time of setting shall be determined with the Vicat 

Apparatus, appaj-^^us described in Section 39. (See Fig. 2.) 
Vicat 48. A paste of normal consistency shall be molded in the 

hard-rubber ring G as described in Section 40, and placed under 

1 Unsoundness is usually manifested by change in volume which causes distortion, 
cracking, checking or disintegration. 

Pats improperly made or exposed to drying may develop what are known as shrinkage 
cracks within the first 24 hours and are not an indication of imsoundness. These conditions 
are illustrated in Fig. 4. 

The failure of the pats to remain on the glass or the cracking of the glass to which the 
pats are attached does not necessarily indicate imsoundness. 



Method. 



Specifications and Tests for Portland Cement. 15 




i 



/^ 




K 


•;,2/ - 


T\ 




• 1 


M^ 






-„9 - 




^ 1 






&> 






t; 






^ 












1 






^ 






b 






^ 






H... 




«g 




iW 



If — 


c 


c^«u* 





hrj-O 


a. 


10 






E 




p 




:t 




o 


Sl 


CQ 






a<7/7^ J9qqn^ 9/q!X&ld ■ 



}fOOQ qouij ++-J. 



16 Specifications and Tests for Portland Cement. 








Specifications and Tests for Portland Cement. 17 

the rod B, the smaller end of which shall then be carefully 
brought in contact with the surface of the paste, and the rod 
quickly released. The initial set shall be said to have occurred 
when the needle ceases to pass a point 5 mm. above the glass 
plate in | minute after being released; and the final set, when 
the needle does not sink visibly into the paste. The test pieces 



(a) Pat with Top Surface Flattened for Determining 
Time of Setting by Gillmore Method. 





I 



'W//////////////////////////////y///y///////////////^^^^ 
(b) Gillmore Needles. 
Fig. 5. 

shall be kept in moist air during the test. This may be accom- 
pHshed by placing them on a rack over water contained in a 
pan and covered by a damp cloth, kept from contact with 
them by means of a wire screen; or they may be stored in a 
moist closet. Care shall be taken to keep the needle clean, as 
the collection of cement on the sides of the needle retards the 



18 Specifications and Tests for Portland Cement. 



penetration, while cement on the point may increase the pene- 
tration. The time of setting is affected not only by the per- 
centage and temperature of the water used and the amount of 
kneading the paste receives, but by the temperature and humid- 
ity of the air, and its determination is therefore only approximate. 
GUimore 49. The time of setting shall be determined by the Gillmore 

Needles. 




















A 












1 



Fig. 6. — Details for Briquette. 

needles. The Gillmore needles should preferably be mounted 
as shown in Fig. 5 (b). 
GiUmore 50. The time of setting shall be determined as follows: 

Method. ^ p^^ Qf j^gg^i- cement paste about 3 in. in diameter and J in. in 
thickness with a fiat top (Fig. 5 (a)), mixed to a normal con- 
sistency, shall be kept in moist air at a temperature maintained 



Specifications and Tests for Portland Cement. 19 



as nearly as practicable at 21° C. (70° F.)- The cement shall be 
considered to have acquired its initial set when the pat will bear, 
without appreciable indentation, the Gillmore needle -^^ in. in 
diameter, loaded to weigh J lb. The final set has been acquired 
when the pat will bear without appreciable indentation, the 
Gillmore needle 2V in. in diameter, loaded to weigh 1 lb. In 
making the test, the needles shall be held in a vertical position, 
and applied lightly to the surface of the pat. 

XIV. TENSION TESTS. 

51. The form of test piece shown in Fig. 6 shall be used. Form of Test 
The molds shall be made of non-corroding metal and have suf- ■^^®*^®' 
ficient material in the sides to prevent spreading during mold- 
ing. Gang molds when used shall be of the type shown in . 

Fig. 7. Molds shall be wiped with an oily cloth before using. 

52. The sand to be used shall be natural sand from Ottawa, standard Sand. 




Fig. 7.— Gang Mold. 

111., screened to pass a No. 20 sieve and retained on a No. 30 
sieve. This sand may be obtained from the Ottawa SiKca Co., 
at a cost of two cents per pound, f. o. b. cars, Ottawa, 111. 

53. This sand, having passed the No. 20 sieve, shall be con- 
sidered standard when not more than 5 g. pass the No. 30 sieve 
after one minute continuous sieving of a 500-g. sample. 

54. The sieves shall conform to the following specifications: 
The No. 20 sieve shall have between 19.5 and 20.5 wires 

per whole inch of the warp wires and between 19 and 21 wires 
per whole inch of the shoot wires. The diameter of the wire 
should be 0.0165 in. and the average diameter shall not be 
outside the limits of 0.0160 and 0.0170 in. 

The No. 30 sieve shall have between 29.5 and 30.5 wires 
per whole inch of the warp wires and between 28.5 and 31.5 
wires per whole inch of the shoot wires. The diameter of the 
wire should be 0.0110 in. and the average diameter shall not 
be outside the limits 0.0105 to 0.0115 in. 



20 Specifications and Tests for Portland Cement. 



Faulty 
Briquettes. 



Molding. 55. Immediately after mixing, the standard mortar shall 

be placed in the molds, pressed in firmly with, the thumbs and 
smoothed off with a trowel without ramming. Additional mor- 
tar shall be heaped above the mold and smoothed off with a 
trowel; the trowel shall be drawn over the mold in such a man- 
ner as to exert a moderate pressure on the material. The mold 
shall then be turned over and the operation of heaping, thumb- 
ing and smoothing off repeated. 

Testing. 56. Tests shall be made with any standard machine. The 

briquettes shall be tested as soon as they are removed from the 
water. The bearing surfaces of the cKps and briquettes shall 
be free from grains of sand or dirt. The briquettes shall be 
carefully centered and the load applied continuously at the rate 
of 600 lb. per minute. 

57. Testing machines should be frequently calibrated in 
order to determine their accuracy. 

58. Briquettes that are manifestly faulty, or which give 
strengths differing more than 15 per cent from the average value 
of all test pieces made from the same sample and broken at 
the same period, shall not be considered in determining the 
tensile strength. 

XV. STORAGE OF TEST PIECES. 

Apparatus. 59. The moist closet may consist of a soapstone, slate or 

concrete box, or a wooden box Hned with metal. If a wooden 
box is used, the interior should be covered with felt or broad 
wicking kept wet. The bottom of the moist closet should be 
covered with water. The interior of the closet should be pro- 
vided with non- absorbent shelves on which to place the test 
pieces, the shelves being so arranged that they may be with- 
drawn readily. 

Methods. 60. Unless otherwise specified all test pieces, immediately 

after molding, shall be placed in the moist closet for from 20 to 
24 hours. 

61. The briquettes shall be kept in molds on glass plates 
in the moist closet for at least 20 hours. After 24 hours in 
moist air the briquettes shall be immersed in clean water in 
storage tanks of non-corroding material. 

62. The air and water shall be maintained as nearly as 
practicable at a temperature of 21° C. (70° F.). 



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